He continued: "I think he would run. Hillary Clinton would be formidable, no question about it, but I’ve known Biden over the years. He is somebody who's always wanted to be president. He’s got the eye of the tiger."

Richardson was the U.S. ambassador to the United Nations under President Bill Clinton. He supported Barack Obama for Democratic presidential nomination in 2008.

He described Clinton as a formidable candidate "who not only is appealing to the Democratic base, but is appealing to a Republican base that acknowledges the great work she did."